A head member of a liquid ejecting apparatus, such as a recording head of an ink-ejecting recording apparatus, has a pressure-generating chamber which is communicated with a nozzle and which is partly formed by an elastic plate. A movable end of a piezoelectric vibrating member is joined to the elastic plate. The piezoelectric vibrating member can expand and contract. Thus, a volume of the pressure-generating chamber can be changed by causing the piezoelectric vibrating member to expand and contract. As a result, ink can be supplied into the pressure-generating chamber and a drop of the ink can be ejected from the pressure-generating chamber.
As an actuator for driving such a recording head at a high speed, a longitudinal-mode piezoelectric vibrating member is used, which consists of alternatively stacked piezoelectric material and electric conductive layer and which can extend in a longitudinal direction thereof.
The longitudinal-mode piezoelectric vibrating member needs a smaller area in order to join to the pressure-generating chamber than a bending-type piezoelectric vibrating member does. In addition, the longitudinal-mode piezoelectric vibrating member can be driven at a higher speed. Thus, a printing operation can be achieved with a finer resolution (definition) and at a higher speed.
However, although such a longitudinal-mode piezoelectric vibrating member can be driven at a higher speed, a reducing rate (damping rate) of remaining vibration (residual vibration) thereof is smaller. Thus, larger remaining vibration may be remained after a drop of the ink has been ejected, which may affect behavior of a meniscus of the ink. For example, if a position of the meniscus remains disordered when a next drop of the ink is ejected, the next drop of the ink may be ejected in an undesired direction. Alternatively, if the meniscus overshoots a proper range toward the nozzle so much, mist of the ink may be generated i.e. quality of printed images may be deteriorated.
Then, in order to prevent generation of the mist of the ink or the like by reducing (damping) the remaining vibration of the meniscus after the drop of the ink is ejected, the Japanese Patent Laid-Open Publication No.9-52360 has proposed an ink-ejecting recording apparatus. The ink-ejecting recording apparatus is adapted to generate a driving signal PDS including: a first signal-element S51 for causing a pressure-generating chamber to expand, a second signal-element S52 for causing the pressure-generating chamber to contract from an expanding state thereof in order to eject a drop of the ink through a nozzle, and a third signal-element S53 for causing the pressure-generating chamber to expand by a volume smaller than a volume expanded by the first signal-element S51 just when a vibration of the meniscus turns toward the nozzle after the drop of the ink is ejected (see FIG. 6). Thus, the meniscus, which is going to turn toward the nozzle after the drop of the ink is ejected, is pulled back toward the pressure-generating chamber because the pressure-generating chamber is caused to expand by the third signal-element S53. Thus, the vibration of the meniscus can be reduced effectively. Thus, the generation of the mist of the ink, which may be caused by movement of the meniscus, can be prevented. In addition, a position of the meniscus can be adjusted to a substantially regular position when a next drop of the ink is ejected, so that the drop of the ink can be ejected more stably.
With respect to the driving signal PDS shown in FIG. 6, a voltage difference Vc1 of the first signal-element S51, a voltage difference Vd of the second signal-element S52 and a voltage difference Vc2 of the third signal-element S53 satisfy a relationship of Vc1+Vc2=Vd.
The driving signal PDS shown in FIG. 6 is designed as follows.
At first, in accordance with characteristics of ejecting a drop of the ink (ejecting weight of the drop of the ink and/or ejecting speed thereof), the voltage difference Vd of the second signal-element S52 is designed. Then, depending on the voltage difference Vd, in order for adjustment of the voltage level, the voltage difference Vc1 of the first signal-element S51 and the voltage difference Vc2 of the third signal-element S53 are designed. Herein, it is taken into consideration that the third signal-element S53 serves for controlling vibrations of menisci. If the vibrations of menisci are suitably controlled, a drop of the ink can be stably ejected in the next period.